poj 3278 Catch That Cow

#include<iostream>            //bfs广度优先搜索
#include<deque>
using namespace std;
struct Node
{
    int data,times;
}node[1000000];
int n,k,p;
bool visited[500000];
int main()
{
    cin>>n>>k;
    deque<Node> col;
    if(n==k)
        cout<<"0\n";
    else
    {
        node[0].data=n;node[0].times=0;
        col.push_back(node[0]);
        visited[n]=1;
    }
    while(!col.empty())
    {
        int d=col.front().data,t=col.front().times;
        col.pop_front();
        if(d-1==k||d+1==k||2*d==k)
        {
            cout<<t+1<<endl;
            break;
        }
        if(d-1>=1 && visited[d-1]==0)
            visited[d-1]=1,node[++p].data=d-1,node[p].times=t+1,col.push_back(node[p]);
        if(visited[d+1]==0)
            visited[d+1]=1,node[++p].data=d+1,node[p].times=t+1,col.push_back(node[p]);
        if(2*d<500000 && visited[2*d]==0)
            visited[2*d]=1,node[++p].data=2*d,node[p].times=t+1,col.push_back(node[p]);
    }
    return 0;
}